I am stumped. I tried to get the rotors off to replace them but the old rotors wont budge. Do I need to take off the axle bolt and if so, what size(in mm) do I use? If not, what can I do to get them off. I have pounded on them with mallets and tried to pry them, all to no sucess. Any help would be appreciated.

No you don't need to remove the axle bolts. I remember the first time taking my rear wheels off I had the same issue. Just keep beating on them until they come off, if that doesn't help have a larger stronger friend try. They will come off eventually, they rust to the wheel hub and suck trying to remove.

Be sure to remove the one Allen bolt that holds the disc to the hub (and of course, the calliper).
Spray around the joint with the hub with an easing spray, and start whacking the old disc with a hammer whilst trying to pull it off.
Don't worry about really whacking the old disc as hard as possible, you are replacing it, in fact the harder you whack it, the quicker it will come off

aam (Albert) will love this advice

No trees were harmed creating this message, however some electrons were very inconvenienced.

Hehehe.. I do like your comment . watch out for E brake and try using fresh COKE to loose the rusty stubborn dish..works for me every single time .

Fresh Coke. Ive heard of that for battery terminals but never tried it on rust. Another one I just heard for rusted bolts was a little heat and candle wax. Allegedly the wax wicks right into the joint. Never tried either of them, Im just the rumor spreader.

Fresh Coke. Ive heard of that for battery terminals but never tried it on rust. Another one I just heard for rusted bolts was a little heat and candle wax. Allegedly the wax wicks right into the joint. Never tried either of them, Im just the rumor spreader.

Fresh Coke works wonders on rust, but you usually have to let the part soak in it for a while. Put a rusty bolt in a glass of fresh (un-opened) Coke and let it sit over night. I can practically garantee you that the bolt will be spanking clean in the morning.

Now, think about what this stuff does to your insides when you drink it...

Do NOT remove the wheel bearing nut.
DO make sure you've removed the allen on the front of the disc
DO make sure you have released the e brake and backed it off at the adjuster
DO spray some penetrating oil between the rotor and hub (PB blaster is good stuff!)
Do heat it if you have a torch (but DO NOT ignite the penetrating oil!)
Finnally, whack it out toward the edges working you way around it with a short hanndled 5 lb sledge. Whack it HARD. It will pop off.